Drilling bit



Aug. 9, 1932. E. w. FORROW DRILLING BIT Filed April 21, 1928 INVENTUR.

ATTORNEY.

Patented Aug. 9, 1932 UNITED STATES PATENT GFFICE 1 ELWIN W. BORROW, 0'5 LOS ANGELES, CALIFORNIA, ASSIGNOR TO BYRON JACKSON (30., 0F LOS ANGELES, CALIFORNIA, A CORPORATION OF DELAVTABE DRILLING IBI'I.

Application filed April 21,

This invention relates to a rotary drilling bit of fish tail type in which there are a plurality of ground engaging teeth, thus provid ing a bit which will remain sharp for a greater length of time and which will out faster than the usual bit having lesser number of teeth.

An object of my invention is to provide a bit which will maintain the proper gauged hole for a greater length of time than in bits heretofore in use. 7

further object is to provide a bit in which the cutting teeth are so arranged that no appreciable core is out and the Water course is so provided that little chance is afforded for packing of the cuttings between the teeth.

Other objects, advantages, and features of my invention may appear from the accompanying drawing, the subjoined detailed description, and the appended claim.

In the drawing.

Fig. 1 is a side elevation of my bit.

Fig. 2 is a side view taken at right-angles to the view shown in Fig. 1.

Fig. 3 is a bottom plan view of the bit.

Referring more particularly to the draw- 1n lhe numeral 1 indicates a body from which a threaded pin 2 rises whereby the bit is coupled to the drill pipe. A substantially flat blade 3 is formed on the lower part of the body 1, which blade is of lesser thickness than the upper part of the body, the central por-' tion of the blade 3 being increased in thickness, as shown at 4, to accommodate the water course 5 which extends longitudinally through the bit.

In the same plane with the blade 3 and at diametrically opposite points, I provide a pair of cutting teeth 5, 6, said teeth being of substantially the same or, a slightly greater length than any of the teeth to be subsequently described. Therefore, these teeth provide a leading edge and enter the formation first and act as scarifiers for the bit. It is obvious that the lower edges of the teeth will quickly be worn away so that after the bit has been drilling for a short time all of the cutting teeth will be in substantially the same plane. The teeth 5, 6 are not of great width,

1928 Serial No. 271,692.

that is, they do not extend to adjacent the central axis of the bit. A second pair of scarifying teeth 7, 8 are provided on the bottom of the bit and are spaced ahead of the teeth 5, 6. The teeth7, 8 are of lesser length than the teeth 5, 6 and are the second pair to engage the ground. These last named teeth are substantially the same width as the teeth 5, .6 and perform substantially the same function although they augment and assist the longer teeth 5, 6.

A pair of blade cutters 9, 10, preferably of the fish-tail type, are provided on the bottom of the bit and are spaced substantially ninety degrees from the teeth 5, 6, respectively. The cutting edges 11, 12 of the cutters 9, 10 extend from adjacent the central axis of the bit to the maximum outer cut of the tool. The inner edges 13, 14c ofthe cutters 9, 10 are spaced together and adjacent the central axis of the bit, thus preventing the formation of a core and will prevent the accumulation of cuttings above the cutters.

An enlarged space 15 is provided above the cutting edges 11, 12 and below the blade portion 18, thus permitting the cuttings to free themselves and also to be washed away by the pressure of the water flowing through the water course 19, which water course opens these cutters are the last to engage the formation. The extreme outer cutting edges of each of the pairs of teeth and cutters 5, 6;,

7, 8; 9, 10 are all substantially on the same circle inscribed from the central axis of the bit, and thus it will be seen that each of the teeth tend to maintain the proper gauge in the hole at all times. That is, all of the teeth are set on gauge and the outer cutting edges act as reamers to keep the hole at the proper diameter. The cutters 5, 6 are provided at their outer edge with a straight reaming edge 16, 17, respectively, and the teeth 7, 8 are provided with reaming edges 18, 18.

Having described my invention, I claim: A rotary drilling bit of fish tail type consisting of a substantially flat blade extending across the full width of the bit, said blade having a downwardly projecting cutting V edge at each side edge of the blade, and projecting forwardly with respect to the direction of rotation of the bit, a cutter tooth at each side of the blade and projecting from the face of the flat blade in a forward direction with respect to the direction of rotation, said last-named cutters extending forwardly and downwardly and terminating in a cutting edge disposed in an inclined direction with respect to the horizontal plane, each of said last named teeth having a substantially radially extending cutter blade projecting from its outer side and disposed in a plane inclined with respect to the vertical line.

In testimony whereof, I affix my si nature. V ELWIN W. FOR OW. 

